Preliminary reports ruled out that seismic sound waves created by oil exploration in that stretch of sea could have killed the birds, the environment ministry said.

CNN: Peru investigates mystery pelican deaths

One of them involved the Joint Maritime Seismic Undertaking (JMSU) in 2004 for oil exploration in the South China Sea, which has been shrouded in controversy, as it may have conceded territorial waters to China.

CENTERFORSECURITYPOLICY: Enter the dragon